Many commercial compositions containing moisture curable silylated polymers are known, and have many commercial applications. For example, silylated polyurethanes are useful as coatings, adhesives, sealants and industrial elastomeric goods.
Silylated polyurethanes are typically prepared by reacting an isocyanate-containing prepolymer with an aminosilane; yielding products having generally high viscosity, and as a consequence, difficult processability. This high viscosity can be related to hydrogen bonding due to the presence of urea and urethane groups, so current solutions have focused on decreasing/eliminating the urethane/urea content in these silylated polyurethanes.
In the art, several methods have been described for decreasing/eliminating the urethane/urea content in silylated polyurethanes.
For example, long chain-polyether polyols can be used for preparing the polyurethane. However, the method requires polyether polyols with a high functionality and a low level of unsaturation and polydispersity and not all the hydrogen bond density can be eliminated.
Another example involves the reaction of OH-functional prepolymer with an isocyanatosilane, yielding an urea-free polyurethane. However, isocyanatosilanes may be objectionable from a toxicological standpoint. Additionally, raw material availability and price are often an issue.
Another example involves the partial or complete allophanatization and/or biuretization of the urethane/urea groups with mono-isocyanates, which sterically hinder hydrogen bond formation. This method however, requires an additional synthetic step after preparation of the silylated polyurethane, which increases production costs. In addition, monoisocyanates have environmental, health and safety issues.
Therefore, there remains a need for silylated polyurethanes and processes to prepare said polyurethanes that overcome one or more of the aforementioned issues. It is an object of the present invention to overcome one or more of the aforementioned issues.